In recent years, environment pollutions, oil resource depletion and global warming have driven people to seek technical break-through in the field of new energy power system. Decision makers in many cities in our country are beginning to plan tramcar construction projects, with power gridless areas being deployed in critical sections in order to preserve urban landscapes. Under the circumstance of high speed of rail transit and popularization of urban rail transit, achievements of energy-saving, environment-friendliness, safety and reliability by researches on energy storage technologies and smart control strategies will be modernization signs of rail transit technology in the new century. For the purpose of achieving friendly and harmonious development of human, environment and vehicles, countries around the world are actively exploring new energy sources, which are bound to become a development trend of future tramcars.
At present, energy storage units maturely applied in hybrid power systems mainly include two categories: super capacitor and power battery. The super capacitor has high power density and is characterized by rapidly charging/discharging, satisfying the power level required by high acceleration and efficiently recovering braking energy. The power battery has high energy density, and is characterized by continuously discharging, satisfying huge energy requirements for long distance travelling and moderately recovering braking energy. Other than these, fuel cells, which are zero-emission, energy saving and environmentally-friendly new energy, have also become a focus and hot spot of technology researches of hybrid power cars and rail vehicle. Hence, a hybrid power system using a fuel cell, a power battery and a super capacitor in a tramcar has become the core of researches. However, said hybrid power system would release a large amount of heat when providing power for the tramcar. Especially, the fuel cell has the maximum heat release, for example, a fuel cell with rated power output of 150 kiloWatt (kW) could release as much as 120-150 kW heat. To dissipate this part of heat, a highly effective heat dissipating device would be desirable.
In prior art, water cooling technologies are employed to reduce temperature of the energy storage units. This, however, has low heat dissipation efficiency, and thus is unable to meet high heat dissipation requirements of the fuel cell.